I agree that it does take time and patience to increase your capacity. My exgirlfriend was very much into enemas when I met her. On our third date, I discovered her enema bag hanging over a coat hanger in her closet between some clothes. As our relationship grew, I eventually ended up giving her enemas using her 2-quart bag. At first, the two quarts seemed to be all she could manage, but within a month of taking enemas a few times per week, her capacity increased.
Of course, I would always start her off with a few 1-quart cleansing enemas. I don't think it is a good idea to start off with a large enema without first being cleansed; otherwise, all that debris would get pushed up into her digestive tract or cause unwanted blockages, which is not a good idea.
After her 2-quart bag was empty, I would refill it and begin again with the bag at a lower level to reduce the flow rate. I got her to relax and not be in such a hurry. With a little patience and rlaxation, the second bag would continue to empty into her belly. At first, her limit seemed to be 2 and 1/2 quarts, but the next couple of times I noticed the second bag was half empty before she would ask me to stop. Eventually, by getting her to be more relaxed, I finally saw the second bag become empty. She said she felt very full but did not feel the need to let it out. I told her that she has now earned the 4-quart mark of achievement.
Previously, after her usual hurried 2-quart enema, her belly did not look any different to me when she stood up. But now with four quarts in her belly, I could really see a difference in the size of her belly. Her belly was pleasantly round, and I especially noticed how her belly button seemed to be more pushed out than usual. Anyway, as the saying goes, patience and practice makes perfect. Perhaps if we were still dating, I could have increased her capacity even more (maybe five quarts), but I guess I will never know.